The present invention relates generally to portable electronic devices, and more particularly to increasing the battery life of portable electronic devices.
For a portable electronic device such as a personal data assistant (PDA), a digital audio player (e.g., an MPEG3 or xe2x80x9cMP3xe2x80x9d player), a digital video player (e.g., a DVD player) or the like to play digital audio or video, or to perform other data intensive operations, a continuous stream of data at rates of up to 1.5 Mbytes/min must be supplied to the portable electronic device. Due to limited internal memory capacity, portable electronic devices typically cannot store sufficient data to sustain continuous data intensive operations (e.g., the playing of digital audio or video) for any meaningful time period (e.g., long enough to play an entire song or video).
To compensate for limited internal memory capacity, most portable electronic devices employ removable storage devices to supply data to the portable, electronic devices. Common removable storage devices include removable disk drives, hard drives or compact flash(trademark) memory devices. As used herein, removable storage devices include devices that may be external to or internal to a portable electronic device.
While removable storage devices contain sufficient memory and dan sustain most data rates required by portable electronic devices, these storage devices also consume significant electrical power and thereby severely reduce the battery life of portable electronic devices. For example, the battery life of a typical PDA running an MP3 player application is about 30-45 minutes if the PDA uses a removable storage device to continuously supply digitized audio data to the PDA. Such a short battery life renders the use of portable electronic devices that perform data intensive operations both expensive and inconvenient.
To address the needs of the prior art, systems, devices, computer program products, and methods are provided which significantly increase the battery life of a portable electronic device that performs data intensive operations such as playing digital audio or video. While particularly beneficial for increasing the battery life of the above described portable electronic devices, the present invention may be employed in other applications including portable DVD players, wearable computers and automobile personal computers.
In a first aspect of the invention, a system is provided that includes a first device that can store data and transfer data (e.g., a removable storage device such as a hard drive, a tape drive, a CD-ROM drive, a DVD drive or a flash memory device such as a compact flash(trademark) memory device, a Smart Media(trademark) or a Memory Stick(trademark)). The first device is capable of transferring data at a first rate. An intermediate storage location (e.g., a cache memory such as a first-in first-out buffer, a random access memory, a static memory or a dynamic memory) is coupled to the first device, and a second device (e.g., a portable electronic device such as a PDA, an MP3 player, a video player, etc.) is coupled both to the first device and to the intermediate storage location. The second device includes a processor that is adapted to execute a computer program that requires, data to be transferred to the processor at a second rate which is lower than the first rate.
Computer program code is provided that can initiate the transfer of data at the first rate from the first device to the intermediate storage location and that can initiate the transfer of data at the second rate from the intermediate storage location to the processor. The intermediate storage location preferably is selected to consume less power when powered on than the first device consumes when powered on. Computer program code preferably is provided to power down the first device following the transfer of data from the first device to the intermediate storage location. As used herein, xe2x80x9cpowered onxe2x80x9d means being in an operational state that is suitable for data transfer (e.g., a state having a spinning hard disk or CD-ROM) and xe2x80x9cpowered downxe2x80x9d means being in an operational state that reduces power consumption, such as a state with all power removed from the device or an idle state (e.g., a state having a stationary hard disk or CD-ROM).
In other aspects of the invention, devices, computer program products and methods are provided for use within (or for use independent from) the above described system. Each inventive computer program product is carried by a medium readable by a computer (e.g., a carrier wave signal, a floppy disc, a hard drive, a random access memory, etc.).